Make sure you state the whole explicitly. For example if you are discussing male and female representation among students, then the ‘whole’ is students. If you want to say that 50% of students are female, do not write 50% of females are students. For a more detailed look at what I mean by the ‘whole’, take a look at my post Don’t forget the whole.

Use this structure with the first two or three numbers that apply to each new theme that you introduce and your reader will understand what the numbers refer to. You will also receive a good score in IELTS in all four criteria.